1. Field of the Invention
This invention relates to a coiler having an expanding core, which comprises a tubular coiler shaft, a plurality of radially adjustably mounted, heatable extensible segments, an expanding mechanism, which extends in the tubular coiler shaft and is operable to extend the extensible segments, and heat insulating material and cooling means extending between the heatable portion of the expanding core and the coiler shaft.
2. Description of the Prior Art
In a coiler in which strip is coiled on a coiler core and is heated from the inside by the coiler core serving as a heater, a formation of scale at elevated temperatures can be substantially avoided and a substantial dissipation of heat can also be avoided. But in such coiler the coiler shaft and the expanding mechanism must be protected from an excessive heat load. For this purpose it is known from Austrian Patent Specification No. 370,777 to divide each extensible segment in height and to separate the two parts of each segment by heat insulating material so that the outer part of each extensible segment can be heated and its inner part can be cooled. In that case the heat which is transferred in spite of the heat insulation can be dissipated by the means for cooling the inner part of each extensible segment so that the expanding mechanism and the coiler shaft are protected from an excessively high heat load. But in such a coiler a heat transfer bridge is constituted by the pressure transmitting bars which are provided between the outer and inner parts of each extensible segment and extend throughout the length of said segment, and by the clamp screws by which the two parts of each extensible segment are forced together. Heat at an appreciable rate is dissipated via said heat transfer bridge and is not available for the reheating of the coiled strip.